tenofovir disoproxil fumarate: clinical use

Prescribing considerations

• Confirm HIV status before treating hepatitis B because unrecognised HIV infection risks selecting resistance if tenofovir is not part of an appropriate combination regimen.
• Review renal impairment, renal risk factors, osteoporosis, previous fractures and concomitant nephrotoxins.
• For treatment-experienced HIV, consider resistance results and treatment history.
• Do not stop hepatitis B treatment without a monitoring plan; severe post-treatment hepatic exacerbations have occurred.
• Granules contain mannitol, which may have a mild laxative effect; the selected film-coated tablet contains lactose.

Contraindications and cautions

• Hypersensitivity to tenofovir disoproxil fumarate or a formulation excipient.
• The selected lactose-containing tablet should not be used in patients with galactose intolerance, total lactase deficiency or glucose-galactose malabsorption.

Monitoring

• Assess creatinine clearance and serum phosphate before treatment and regularly thereafter; increase monitoring with renal risk factors or interacting medicines.
• Investigate progressive renal decline, hypophosphataemia, glycosuria, hypokalaemia, muscle weakness or bone pain for proximal tubulopathy.
• Monitor virological response and relevant HIV or hepatitis B laboratory markers.
• After hepatitis B treatment stops, monitor clinical status, liver function and HBV markers for hepatic flare.
• In children, consider long-term renal and bone uncertainty within multidisciplinary benefit–risk review.

Clinical pharmacology

Tenofovir disoproxil is an orally absorbed ester prodrug converted to tenofovir and intracellular tenofovir diphosphate. The active metabolite terminates viral DNA chains and is eliminated mainly through renal filtration and active tubular secretion, with low potential for CYP450-mediated interactions.

Formulation and product differences

• The selected film-coated tablet is taken with food and may exceptionally be dispersed in specified drinks; it contains lactose.
• Granules are intended for people for whom a solid dosage form is unsuitable, including eligible younger children. They must be measured with the supplied scoop, mixed with soft food and not mixed with liquid.
• Granules contain mannitol and may have a mild laxative effect.

Granules

Route: Oral

Strengths: 33 mg/g

Tablet

Route: Oral

Strengths: 123 mg, 163 mg, 204 mg, 245 mg